How to cure paint that won't dry?

DeltaVee · Post by **DeltaVee** » Sun Jun 29, 2014 1:15 pm

I have 3 of the same 3D printed model. I've repainted 2 of them at least 3 times because the paint won't dry in 2 areas - same place on both models. I've been using Floquil enamels. This last time I stripped both models down to the base material and repainted with Gunze spray primer and they seemed to dry. Then I painted and got the same non-dried paint. It's not like this is uncured resin.
If I spray a coat of Future over them - as I plan to anyway for a wash - will that just seal the sticky paint in place, and I can finish the job?

tonyG2 · Post by **tonyG2** » Sun Jun 29, 2014 2:22 pm

Have you tried acrylics?

DeltaVee · Post by **DeltaVee** » Sun Jun 29, 2014 5:48 pm

I've not tried acrylic paint on these. Hate to strip down to the bare nylon and try again. I prefer enamels, and in this case, I wanted to paint these a mix of Floquil reefer white and grime that I like.

Rogviler · Post by **Rogviler** » Sun Jun 29, 2014 11:46 pm

Enamel over nylon sometimes does the same as enamel over vinyl I've found, i.e. it doesn't dry and will remain sticky forever. I had that happen recently on something I thought was ABS, but turned out to be nylon. The only safe option is to strip it and come back with an acrylic I think. I've tried sealing it before (on vinyl though), and while that fixed it temporarily, it eventually became sticky again.

-Rog

chasd25 · Post by **chasd25** » Mon Jun 30, 2014 11:17 am

When we paint printed nylon at the shop we use either feather fill (polyester based filling primer), or a true lacquer automotive primer, Du-pont 131S.

Could try Tamiya white primer or Gunze Mr. Surfacer, both in spray cans, they are both lacquer based.

DeltaVee · Post by **DeltaVee** » Mon Jun 30, 2014 12:13 pm

Thanks guys. Chad, I did prime it with Gunz Mr. Surfacer or Primer Surfacer, which I understand is laquer based and rumored to regular Dupont auto primer in a smaller, more expensive quantity. The primer dried, so I re-sprayed and the same areas still had soft paint. That's what threw me.

chasd25 · Post by **chasd25** » Tue Jul 01, 2014 4:47 pm

DeltaVee wrote:Thanks guys. Chad, I did prime it with Gunz Mr. Surfacer or Primer Surfacer, which I understand is laquer based and rumored to regular Dupont auto primer in a smaller, more expensive quantity. The primer dried, so I re-sprayed and the same areas still had soft paint. That's what threw me.

That is odd...the only thing I could recommend is giving it time to dry out, and see what happens. You could make a Hot box out of a foil lined file box, with a light bulb for heat. We used to do that for quick drying/curing. We now have a "Hot Room" that maintains about 100-120 degrees for drying paints, curing parts.

Stu Pidasso · Post by **Stu Pidasso** » Tue Jul 01, 2014 5:25 pm

Malcolm M · Post by **Malcolm M** » Thu Jul 03, 2014 2:37 am

Sorry can't help you with the paint as I'm in the same boat. I ordered an M1918 tank from Shapeways, cleaned throughly, primed and then painted with Testors enamels. Two weeks later it still isn't cured.

Personally I think enamel paint and 3D printing plastic hate each other. I'm going to have to strip it off and use Acrylics.

chasd25 · Post by **chasd25** » Thu Jul 03, 2014 3:12 pm

Keep us posted, I'm interested in how this turns out. Our shop paints ALOT of printed parts....going back 15+ years to the first SLA stuff, never saw anything like this happen.

Never anything from shape ways, so I don't know what they are printing stuff in. We're painting polyjet parts off Objet machines, SLS Nylon, SLA, etc...all using automotive acrylic lacquers, never had any issues.

Charlie

E-Dub · Post by **E-Dub** » Fri Oct 31, 2014 8:31 pm

I had this happen once with Testors spray. Two weeks in the basement bathroom with the dehumidifier going constantly finally took care of it.